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[S390] Introduce get_clock_fast() 

Add get_clock_fast() which uses the slightly faster stckf if available.
If stckf is not available fall back to stck, which has the same width.

Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Jan Glauber 2011-10-30 15:17:04 +01:00 committed by Martin Schwidefsky
parent 388186bc92
commit 80376f347d
1 changed files with 11 additions and 0 deletions
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11
arch/s390/include/asm/timex.h
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@ -86,6 +86,17 @@ static inline void get_clock_ext(char *clk)
asm volatile("stcke %0" : "=Q" (*clk) : : "cc");
}
static inline unsigned long long get_clock_fast(void)
{
unsigned long long clk;
if (test_facility(25))
asm volatile(".insn s,0xb27c0000,%0" : "=Q" (clk) : : "cc");
else
clk = get_clock();
return clk;
}
static inline unsigned long long get_clock_xt(void)
{
unsigned char clk[16];